Chapter 9
Nevertheless, we should not endeavour to assume from how many places they are confuted, who are confuted by elenchi, without the science of all things, which, however, belongs to no one art, since there are perhaps infinite sciences, so that evidently there are also infinite demonstrations. Still there are also true elenchi, for in whatever it is possible to demonstrate, we may also therein confute him who lays down a contradiction of the truth, as if he asserted the diameter of a square to be commensurate with its side, a person might confute him by showing it incommensurate. Wherefore, it will be necessary to be scientifically cognizant of all, for some (elenchi) will be from geometrical principles, and their conclusions; others from medical principles; others from those of other sciences; moreover, false elenchi are similarly amongst infinites, since according to each art there is a false syllogism, as the geometrical in geometry, and the medical, (false syllogism) in medicine. Now I mean by according to art, that which is according to the principles of that art, therefore it is evident that places are not to be assumed of all elenchi, but of those which belong to dialectic, since these are common to every art and faculty. It is also, indeed, the province of the man of science to investigate the elenchus which is in each science, whether it is only apparent, not real, and if it is, why it is; but that (elenchus) which is from things common, and does not fall under any art, belongs to dialectics. For if we have those particulars from which probable syllogisms
